1. Field of the Invention
The present invention relates, in general, to an ammunition round for use with rifled or non-rifled barrels, and more particularly, to a hollow bullet adapted for use as a slug projectile.
2. Description of the Related Art
Regardless of whether used in hunting, military, or law enforcement applications, conventional bullets utilize a cartridge structure, where the projectile (or a plurality of projectiles) and its propellant are encased in a single package. The external dimension of a bullet cartridge and/or the projectile is dimensioned such that its outer dimension is nominally the same as the internal diameter of the rifle or gun barrel. This is a necessary design consideration in order to create a seal between the bullet and the barrel for preventing the escape of gas generated by the propellant once it is fired. Most conventional bullets are specifically designed for use with either rifled or non-rifled barrels. Bullets for use in rifled barrels usually have a solid core with a surrounding metal jacket. Typically, the solid core is made from a relatively heavy metal, such as lead, and the jacket is made from a harder material that is capable of withstanding higher temperature, such as copper. In this manner, the copper jacket of the bullet is slightly compressed during its passage down the barrel by the helical grooves in the rifled barrel. The bullet is spun by the grooves to stabilize its flight. Jacketed bullets are capable of withstanding high firing velocities and can achieve high accuracy over long firing ranges.
Certain bullet designs utilized with rifled barrels may have a hollow projectile that has a pit or hollowed-out shape at its tip. Generally, these types of bullets are intended to cause the bullet to fragment upon impact, such that most of the bullet's kinetic energy is expended upon impact. When a bullet of this kind strikes a target, the bullet widens at its tip to increase the frontal surface area of the bullet and limit its depth of penetration. Other collapsible bullet designs have cutout portions which collapse and expand once the bullet strikes a target. Within the prior art, U.S. Pat. Nos. 1,084,342; 1,084,343; and 1,081,616 to Johnson illustrate this type of bullet. These types of bullets feature openings that have portions of the core extruded out and have a tip portion that is prevented from rotational or longitudinal movement until the inner part of the tip near the extruded portions is weakened upon impact to allow for a “mushrooming” effect.
Regardless of whether the firing weapon has a rifled or non-rifled barrel, an important design consideration in making bullets is maximizing the external diameter of the bullet with respect to the inner diameter of the barrel without creating excessive friction during firing. A considerable amount of energy created by the propellant being fired is lost through the friction of the bullet as it travels through the barrel. The friction generates a significant amount of heat and exerts a tremendous pressure on the bullet as it travels through the barrel. One solution for coping with the high temperature and pressure is to use a metal jacket that is capable of withstanding these factors. While this solution is easily applicable to bullets having a solid internal core, it is less practical for use with bullets having a hollow internal structure. In such case, the high pressure exerted on the bullet is sufficient to deform the portions between the hollowed spaces, regardless of whether a metal jacket is used. A bullet that is deformed after it exits the weapon barrel is subject to unpredictable aerodynamics, which reduces its accuracy. Moreover, a bullet that is deformed while traveling within the weapon barrel can often cause internal damage to the helical grooves in the barrel or, at worst, cause the barrel to bulge or burst.
Within the art of shotgun-fired ammunition, conventional shotgun slug designs are typically based on a solid lead core positioned within a plastic shell casing. The interior of the shell casing is filled with powder and buffer material. In some embodiments, the solid lead core may be positioned within a sabot. Conventional shotgun slugs do not have a hollow internal structure.
With reference to FIG. 1, a hollow bullet 10 in accordance with a prior art embodiment is shown. Bullet 10 has a cylindrical body portion 20 and a conical tip 30 monolithically formed with body portion 20. Conical tip 30 may have a pointed terminal surface 40. Alternatively, the conical tip 30 may terminate at a blunt surface. A recess 50 is provided on conical tip 30 and extends through the entire conical tip 30 to form a hollow internal cavity 60. Internal cavity 60 is entirely void of any structure extending across its interior. Such bullet design is described in U.S. Pat. Nos. 1,084,342; 1,084,343; 1,081,616, all to Johnson.
A major disadvantage of such design is that the high pressure exerted on bullet 10 during firing is sufficient to deform conical tip 30. This collapses the recess 50 and deforms the bullet 10 before it exits the barrel and occurs regardless of whether a metal jacket is used. As noted above, bullet 10 that is deformed after it exits the weapon barrel is subject to unpredictable aerodynamics, which reduces its accuracy. Moreover, bullet 10 that is deformed while traveling within the weapon barrel can often cause internal damage to the helical grooves in the barrel or, at worst, cause the barrel to bulge or burst.
It will readily be appreciated by those skilled in the art that the problems associated with existing bullet designs with hollow internal structure call for a solution that is not readily available within the prior art.